Diabetes is a condition characterized by abnormal insulin secretion and a variety of metabolic and vascular manifestations reflected in a tendency toward inappropriately elevated blood glucose levels and which if left poorly treated or untreated can result in accelerated, nonspecific atherosclerosis, neuropathy and thickened capillary lamina causing renal and retinal impairment. Diabetes is characterized as being insulin dependent (Type I) and non-insulin dependent (Type II). Type I diabetes is due to damage and eventual loss of the .beta.-cells of the pancreatic islets of Langerhans with a resulting loss of insulin production. Type II diabetics secrete insulin, however, the insulin is somehow not properly or effectively utilized in the metabolism of blood sugars and glucose accumulates in the blood to above normal levels. This condition is termed insulin resistance.
With the certainty of serious complications resulting from high glucose levels in poorly controlled or uncontrolled diabetics, means to lower blood glucose have been research goals for a considerable period of time. With Type I diabetes glucose control can only be achieved with daily insulin injections. With Type II diabetes glucose control can be effected from a combination of diet and drugs which lower glucose levels. The currently available oral hypoglycemic agents are not completely satisfactory since they may not offer complete blood glucose control or may provide a variety of undesirable side effects or they may elevate insulin concentrations to undesirable and dangerous levels. Thus, the search for improved oral hypoglycemic agents is a continuing one.
The compounds of the present invention are substituted pyridines. The literature discloses a number of substituted pyridines which in some cases are structurally similar to the present compounds; however no suggestion is made of hypoglycemic activity.
German Pat. DE No. 2345422 and its U.S. equivalent U.S. Pat No. 3,948,898 disclose 1-(6-Methyl-2-pyridyl)piperazine (1) and 1-(4-Methyl-2-pyridyl)piperazine (2) as intermediates in the preparation of 2-(piperazinylalkyl)isoquinolinediones ##STR2##
German Pat. DE No. 2362553 and its U.S. equivalent U.S. Pat. No. 4,017,622 disclose 6-(4-methyl-1-piperazinyl)-2-pyridinamine (3) which was used as an intermediate in the preparation of other piperazine derivatives, having antibacterial activities. ##STR3##
U.S. Pat. No. 3,773,951 discloses 1-(2-pyridyl)piperazine as an antidepressant.